* [PATCH] NFS/flexfiles: Replace one-element array with flexible-array member
@ 2024-08-17 14:20 Thorsten Blum
2024-08-17 20:40 ` Trond Myklebust
0 siblings, 1 reply; 3+ messages in thread
From: Thorsten Blum @ 2024-08-17 14:20 UTC (permalink / raw)
To: anna, jlayton, bcodding, kolga, josef, gustavoars, kees
Cc: linux-nfs, linux-kernel, linux-hardening, Thorsten Blum
Replace the deprecated one-element array with a modern flexible-array
member in the struct nfs4_flexfile_layoutreturn_args.
Adjust the struct size accordingly.
There are no binary differences after this conversion.
Link: https://github.com/KSPP/linux/issues/79
Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
---
fs/nfs/flexfilelayout/flexfilelayout.c | 2 +-
fs/nfs/flexfilelayout/flexfilelayout.h | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c b/fs/nfs/flexfilelayout/flexfilelayout.c
index 39ba9f4208aa..fc698fa9aaea 100644
--- a/fs/nfs/flexfilelayout/flexfilelayout.c
+++ b/fs/nfs/flexfilelayout/flexfilelayout.c
@@ -2224,7 +2224,7 @@ ff_layout_prepare_layoutreturn(struct nfs4_layoutreturn_args *args)
struct nfs4_flexfile_layoutreturn_args *ff_args;
struct nfs4_flexfile_layout *ff_layout = FF_LAYOUT_FROM_HDR(args->layout);
- ff_args = kmalloc(sizeof(*ff_args), nfs_io_gfp_mask());
+ ff_args = kmalloc(struct_size(ff_args, pages, 1), nfs_io_gfp_mask());
if (!ff_args)
goto out_nomem;
ff_args->pages[0] = alloc_page(nfs_io_gfp_mask());
diff --git a/fs/nfs/flexfilelayout/flexfilelayout.h b/fs/nfs/flexfilelayout/flexfilelayout.h
index f84b3fb0dddd..a269753f9a46 100644
--- a/fs/nfs/flexfilelayout/flexfilelayout.h
+++ b/fs/nfs/flexfilelayout/flexfilelayout.h
@@ -115,7 +115,7 @@ struct nfs4_flexfile_layoutreturn_args {
struct nfs42_layoutstat_devinfo devinfo[FF_LAYOUTSTATS_MAXDEV];
unsigned int num_errors;
unsigned int num_dev;
- struct page *pages[1];
+ struct page *pages[];
};
static inline struct nfs4_flexfile_layout *
--
2.46.0
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] NFS/flexfiles: Replace one-element array with flexible-array member
2024-08-17 14:20 [PATCH] NFS/flexfiles: Replace one-element array with flexible-array member Thorsten Blum
@ 2024-08-17 20:40 ` Trond Myklebust
2024-08-17 21:17 ` Thorsten Blum
0 siblings, 1 reply; 3+ messages in thread
From: Trond Myklebust @ 2024-08-17 20:40 UTC (permalink / raw)
To: kees, thorsten.blum, bcodding, anna, josef, jlayton, kolga, gustavoars
Cc: linux-nfs, linux-kernel, linux-hardening
On Sat, 2024-08-17 at 16:20 +0200, Thorsten Blum wrote:
> Replace the deprecated one-element array with a modern flexible-array
> member in the struct nfs4_flexfile_layoutreturn_args.
>
> Adjust the struct size accordingly.
>
> There are no binary differences after this conversion.
>
> Link: https://github.com/KSPP/linux/issues/79
> Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
> ---
> fs/nfs/flexfilelayout/flexfilelayout.c | 2 +-
> fs/nfs/flexfilelayout/flexfilelayout.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c
> b/fs/nfs/flexfilelayout/flexfilelayout.c
> index 39ba9f4208aa..fc698fa9aaea 100644
> --- a/fs/nfs/flexfilelayout/flexfilelayout.c
> +++ b/fs/nfs/flexfilelayout/flexfilelayout.c
> @@ -2224,7 +2224,7 @@ ff_layout_prepare_layoutreturn(struct
> nfs4_layoutreturn_args *args)
> struct nfs4_flexfile_layoutreturn_args *ff_args;
> struct nfs4_flexfile_layout *ff_layout =
> FF_LAYOUT_FROM_HDR(args->layout);
>
> - ff_args = kmalloc(sizeof(*ff_args), nfs_io_gfp_mask());
> + ff_args = kmalloc(struct_size(ff_args, pages, 1),
> nfs_io_gfp_mask());
> if (!ff_args)
> goto out_nomem;
> ff_args->pages[0] = alloc_page(nfs_io_gfp_mask());
> diff --git a/fs/nfs/flexfilelayout/flexfilelayout.h
> b/fs/nfs/flexfilelayout/flexfilelayout.h
> index f84b3fb0dddd..a269753f9a46 100644
> --- a/fs/nfs/flexfilelayout/flexfilelayout.h
> +++ b/fs/nfs/flexfilelayout/flexfilelayout.h
> @@ -115,7 +115,7 @@ struct nfs4_flexfile_layoutreturn_args {
> struct nfs42_layoutstat_devinfo
> devinfo[FF_LAYOUTSTATS_MAXDEV];
> unsigned int num_errors;
> unsigned int num_dev;
> - struct page *pages[1];
> + struct page *pages[];
> };
>
> static inline struct nfs4_flexfile_layout *
NACK. There is no advantage to using a flexible array here. Indeed,
you're replacing something that is correctly dimensioned (we only ever
use 1 page), and that can be easily bounds checked by the compiler with
something that has neither property.
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH] NFS/flexfiles: Replace one-element array with flexible-array member
2024-08-17 20:40 ` Trond Myklebust
@ 2024-08-17 21:17 ` Thorsten Blum
0 siblings, 0 replies; 3+ messages in thread
From: Thorsten Blum @ 2024-08-17 21:17 UTC (permalink / raw)
To: Trond Myklebust
Cc: kees, bcodding, anna, josef, jlayton, kolga, gustavoars,
linux-nfs, linux-kernel, linux-hardening
On 17. Aug 2024, at 22:40, Trond Myklebust <trondmy@hammerspace.com> wrote:
> On Sat, 2024-08-17 at 16:20 +0200, Thorsten Blum wrote:
>> Replace the deprecated one-element array with a modern flexible-array
>> member in the struct nfs4_flexfile_layoutreturn_args.
>>
>> Adjust the struct size accordingly.
>>
>> There are no binary differences after this conversion.
>>
>> Link: https://github.com/KSPP/linux/issues/79
>> Signed-off-by: Thorsten Blum <thorsten.blum@toblux.com>
>> ---
>> fs/nfs/flexfilelayout/flexfilelayout.c | 2 +-
>> fs/nfs/flexfilelayout/flexfilelayout.h | 2 +-
>> 2 files changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/nfs/flexfilelayout/flexfilelayout.c
>> b/fs/nfs/flexfilelayout/flexfilelayout.c
>> index 39ba9f4208aa..fc698fa9aaea 100644
>> --- a/fs/nfs/flexfilelayout/flexfilelayout.c
>> +++ b/fs/nfs/flexfilelayout/flexfilelayout.c
>> @@ -2224,7 +2224,7 @@ ff_layout_prepare_layoutreturn(struct
>> nfs4_layoutreturn_args *args)
>> struct nfs4_flexfile_layoutreturn_args *ff_args;
>> struct nfs4_flexfile_layout *ff_layout =
>> FF_LAYOUT_FROM_HDR(args->layout);
>>
>> - ff_args = kmalloc(sizeof(*ff_args), nfs_io_gfp_mask());
>> + ff_args = kmalloc(struct_size(ff_args, pages, 1),
>> nfs_io_gfp_mask());
>> if (!ff_args)
>> goto out_nomem;
>> ff_args->pages[0] = alloc_page(nfs_io_gfp_mask());
>> diff --git a/fs/nfs/flexfilelayout/flexfilelayout.h
>> b/fs/nfs/flexfilelayout/flexfilelayout.h
>> index f84b3fb0dddd..a269753f9a46 100644
>> --- a/fs/nfs/flexfilelayout/flexfilelayout.h
>> +++ b/fs/nfs/flexfilelayout/flexfilelayout.h
>> @@ -115,7 +115,7 @@ struct nfs4_flexfile_layoutreturn_args {
>> struct nfs42_layoutstat_devinfo
>> devinfo[FF_LAYOUTSTATS_MAXDEV];
>> unsigned int num_errors;
>> unsigned int num_dev;
>> - struct page *pages[1];
>> + struct page *pages[];
>> };
>>
>> static inline struct nfs4_flexfile_layout *
>
> NACK. There is no advantage to using a flexible array here. Indeed,
> you're replacing something that is correctly dimensioned (we only ever
> use 1 page), and that can be easily bounds checked by the compiler with
> something that has neither property.
I see. Why is it an array then and not just a pointer to a struct?
Thanks,
Thorsten
^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-08-17 14:20 [PATCH] NFS/flexfiles: Replace one-element array with flexible-array member Thorsten Blum
2024-08-17 20:40 ` Trond Myklebust
2024-08-17 21:17 ` Thorsten Blum
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